Conformational stress and anastomotic hyperplasia

Area of Science:

• Biomedical Engineering
• Vascular Surgery
• Pathology

Background:

• Late failure of synthetic vascular grafts in small arteries (<4mm) is often caused by anastomotic hyperplasia.
• Anastomotic hyperplasia is theorized to result from arterial wall stress due to conformational changes at the graft-artery connection.

Purpose of the Study:

• To investigate the role of increased arterial wall tension in causing anastomotic hyperplasia.
• To model the conformational changes at a synthetic graft anastomosis in a rabbit infrarenal aorta model.

Main Methods:

• A plastic insert was implanted into the infrarenal aorta of nine rabbits to induce conformational changes and increase arterial wall tension (80-100%).
• Aortography, ultrasound, and CT scans were used to assess the aorta and confirm insert placement and conformational changes.
• Aortic tissues were analyzed after implantation periods ranging from 3 days to 6 months.

Main Results:

• Rabbits with inserts for 1-6 months developed subintimal hyperplastic lesions consistent with anastomotic hyperplasia.
• Two rabbits with inserts removed after 1 minute showed complete aortic healing without hyperplasia.
• The induced arterial wall conformational changes and increased tension correlated with lesion formation.

Conclusions:

• Arterial wall conformational changes leading to increased tension may be the primary stimulus for anastomotic hyperplasia.
• Preventing anastomotic hyperplasia may necessitate graft-artery connection methods that do not elevate arterial wall tension.